1. Field
The present embodiments relate to a perpendicular magnetic recording head and a method of manufacturing the perpendicular magnetic recording head.
2. Related Art
Generally, a magnetic head device includes a longitudinal recording (in-plane recording) magnetic head device that applies a magnetic field parallel to a recording medium thereto to perform a recording operation, and a perpendicular magnetic recording head device that applies a magnetic field perpendicular to a recording medium thereto to perform a recording operation. The perpendicular magnetic recording head device is further suitable to increase the recording density.
As commonly known, the perpendicular magnetic recording head has a structure in which a main magnetic pole layer and a return path layer are laminated with a non-magnetic insulating layer therebetween at a surface facing a recording medium. The main magnetic pole layer and the return path layer are magnetically connected to each other at the rear of a surface facing a recording medium (hereinafter, referred to as a medium facing surface) in a height direction. Coil layers for applying a recording magnetic field to the main magnetic pole layer and the return path layer are provided in the non-magnetic insulating layer.
When current is supplied to the coil layers, a recording magnetic field is induced between the main magnetic pole layer and the return path layer. In this case, the recording magnetic field is perpendicularly applied to a hard film of the recording medium from the front end surface of the main magnetic pole layer exposed to the medium facing surface, and the recording magnetic field returns to the return path layer through a soft layer of the recording medium. As a result, a magnetic recording is performed at a portion facing the main magnetic pole layer. The above-mentioned perpendicular magnetic recording head is disclosed in JP-A-2005-122831.
A so-called shielded pole structure has been proposed in recent years. In the shielded pole structure, a distance (gap) between the main magnetic pole layer and the return path layer is small, for example, about 50 nm on the surface facing the recording medium to obtain a magnetic recording head that suppresses the dispersion of the magnetic flux from the main magnetic pole layer toward the return path layer so as to have little blur.
In the perpendicular magnetic recording head having the shielded pole structure, the depth of the return path layer in a depth direction (throat height), as well as the gap, are important parameters used to control the recording magnetic field (control an intensity and gradient of the recording magnetic field), and need to be appropriately adjusted.
When the throat height is small, as in the related art, an area of the main magnetic pole layer facing the return path layer decreases. Accordingly, since the magnetic flux from the main magnetic pole layer toward the return path layer is likely to leak, the intensity of the recording magnetic field increases. However, since the magnetic flux returning from the main magnetic pole layer toward the return path layer is likely to be dispersed, it is difficult to sufficiently increase the gradient of the magnetic field.
Alternatively, when the throat height is large, an area of the main magnetic pole layer facing the return path layer increases. Accordingly, since the magnetic flux is likely to flow from the main magnetic pole layer toward the return path layer, the gradient of the magnetic field is improved. However, since the magnetic flux from the main magnetic pole layer toward the return path layer decreases, the gradient of the magnetic field decreases. As the intensity of the recording magnetic field increases, the gradient of the recording magnetic field decreases. When the gradient of the recording magnetic field increases, the intensity of the recording magnetic field decreases. Therefore, it is not possible to improve the intensity and the gradient of the recording magnetic field at the same time.